Tag Archives: issues

1.) New images taken by the Gaia SM (Sky Mapper) CCDs were just published by ESA. There are images of the cluster NGC 2516, the spiral galaxy Messier 94 and Cat’s Eye Nebula available. Enjoy the new images here:

The spiral galaxy M94 as seen by two SM CCDs. You can clearly recognize the gap between the two CCD chips. Most likely this is the last time that images of these kind of extended objects are downloaded, as Gaia will observe only point sources during nominal observations.

2.) There are some more news about the status of Gaia available now in an article by my colleague Stefan Jordan in the German journal ‘Sterne und Weltraum’. The commissioning is ongoing quite well and will continue until May at least.

Two issues are mentioned for the first time (I think) in this article:

There was a problem with one thruster of the MPS, the Micro Propulsion System. It was delivering much more thrust than desired. But the issue was solved very quickly by a recalibration of the nitrogen supply mechanism.

A contamination issue was detected for one of the mirrors reducing the throughput of the affected telescope by more than the half. The contaminant has still to be determined, but the contamination was already successfully cleaned by heating this particular mirror. Investigations are ongoing to identify the contaminant to make sure that a similar scenario cannot happen again. It is not ruled out that there is a correlation to the stray light issue (more information about this here https://hvossgaia.wordpress.com/2014/02/12/gaia-status-update-after-one-month-of-commissioning/). Parts of the thermal tent are most likely heated by the stray light and an increased outgassing of the paint used for the thermal tent could be an explanation for the contamination seen. But other scenarios are still under investigation. Most likely we will learn more about the issue after next Monday, when the sun aspect angle of Gaia is changed by three degrees to reduce the stray light effect. Let us keep the fingers crossed that this manoeuvre will yield the desired results. 😉

All these are small issues normal for the initial phase of a space mission. In Germany we call it ‘Kinderkrankheiten’ – these kind of not so serious illnesses that small children are suffering from. Solutions were found and in most cases already applied. Overall, the mission progress is quite impressive.